There are apparatuses known in the related art, for a working vehicle having an HST (hydrostatic transmission) travel circuit and a working circuit such as a wheel loader, that limit the maximum displacement of a traveling hydraulic motor in correspondence to the discharge pressure of a working hydraulic pump so as to reduce travel driving force (refer to, for example, Patent Reference Literature #1). In the apparatus disclosed in Patent Reference Literature #1, an HST pump and a working hydraulic pump are each driven by an engine, and the pump discharge amount changes according to the engine rotation speed. Travel drive pressure of the HST circuit is limited by a relief valve.    Patent Reference Literature 1: Japanese Patent Publication No. 2818474